Substrate processing apparatus and substrate processing method

ABSTRACT

When a substrate W is processed, a cover member covers a peripheral portion of the upper surface of the substrate held by the substrate holding unit, and a central portion of the substrate located at an inner position than the peripheral portion in a radial direction is exposed without being covered by the cover member. A gap is formed between the lower surface of the cover member and the peripheral portion of the upper surface of the substrate held by the substrate holding unit. When the interior space of the cup is exhausted, a gas present above the interior space of the cup is introduced from a space enclosed by the internal peripheral surface of the cover member through the gap into the interior space of the cup.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority from Japanese PatentApplication No. 2012-235982, filed on Oct. 25, 2012 with the JapanPatent Office, the disclosure of which is incorporated herein in itsentirety by reference.

TECHNICAL FIELD

The present disclosure relates to a substrate processing apparatus and asubstrate processing method for processing a peripheral portion of arotating substrate by supplying a processing liquid to the peripheralportion.

BACKGROUND

A manufacturing process of semiconductor devices includes a peripheralportion cleaning process of removing an unnecessary film or contaminantsfrom a peripheral portion of a semiconductor wafer (hereinafter, simplyreferred to as a “wafer”), which is a target substrate, by supplying aprocessing liquid such as a chemical liquid to the peripheral portion ofthe wafer while rotating the wafer. Such a cleaning is called as a bevelcleaning or an edge cleaning.

Japanese Patent Application Laid-Open No. 2012-84856 discloses a liquidprocessing apparatus for cleaning a peripheral portion. The liquidprocessing apparatus includes a vacuum chuck configured to hold a waferhorizontally and rotate the wafer around a vertical axis, a nozzleconfigured to eject a chemical liquid onto the peripheral portion of therotating wafer, a cup configured to surrounds the periphery of the waferto receive a processing liquid scattered from the wafer, and adisc-shaped cover member configured to the upper side of the uppersurface of the wafer and seal the upper surface of the cup in closeproximity to the upper surface. A chimney-shaped intake pipe is providedfrom the central portion of the upper surface of the cover member.Further, the cover member is provided with a protrusion that protrudesdownward at a position just above the peripheral portion of the wafer.Since the interior space of the cup is at a negative pressure by beingevacuated, a down flow of clean air flowing through a housing is suckedfrom the intake pipe, flows through a space between the upper surface ofthe wafer and the lower surface of the cover member towards theperipheral portion of the wafer, and flows through a narrow gap formedbetween the protruding portion of the cover member and the upper surfaceof the wafer into the inside of the cup. By this gas flow, the mist ofthe chemical liquid scattered towards the outside of the wafer isprevented from being attached again to the upper surface of the waferand contaminating the upper surface of the wafer (device formingsurface).

However, since the cover member of Japanese Patent Application Laid-OpenNo. 2012-84856 covers the entire surface of the wafer, the flowresistance from the inlet of the intake pipe to the cup is large. As aresult, unless the interior space of the cup is exhausted strongly, agas flow with a sufficient flow rate may not be obtained at the outletof the narrow gap.

SUMMARY

The present disclosure provides a substrate processing apparatusincluding: a substrate holding unit configured to hold a substratehorizontally; a rotation driving mechanism configured to rotate thesubstrate holding unit around a vertical axis; a processing liquidnozzle configured to supply a processing liquid to a peripheral portionof the substrate held by the substrate holding unit; a cup configured toreceive the processing liquid scattered outwardly from the substrate,the cup having an upper opening and enclosing the periphery of thesubstrate held by the substrate holding unit; an exhaust port configuredto exhaust the interior space of the cup; and a ring-shaped cover memberhaving a lower surface and an internal peripheral surface, in which thecover member covers the peripheral portion of the upper surface of thesubstrate held by the substrate holding unit, a central portion of thesubstrate located at an inner position than the peripheral portion in aradial direction is exposed without being covered by the cover member, agap is formed between the lower surface of the cover member and theperipheral portion of the upper surface of the substrate held by thesubstrate holding unit, and when the interior space of the cup isexhausted, a gas present above the interior space of the cup isintroduced from a space enclosed by the internal peripheral surface ofthe cover member through the gap into the interior space of the cup.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional side view of a liquidprocessing apparatus according to an exemplary embodiment of the presentdisclosure.

FIG. 2 is a plan view illustrating a cover member, an elevationmechanism and a supplying unit of the liquid processing apparatusillustrated in FIG. 1.

FIG. 3 is a cross-sectional view illustrating a region in the vicinityof an external periphery of the right wafer in FIG. 1 in detail in anenlarged scale.

FIG. 4A and FIG. 4B are explanatory views of a nozzle.

FIG. 5A and FIG. 5B are views illustrating the flows of a processingfluid inside and in the vicinity of a cup. FIG. 5A is a viewillustrating flows of liquids, and FIG. 5B is a view illustrating flowsof air current and mist entrained in the air current.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. The illustrativeembodiments described in the detailed description, drawing, and claimsare not meant to be limiting. Other embodiments may be utilized, andother changes may be made, without departing from the spirit or scope ofthe subject matter presented here.

The present disclosure provides a technique capable of effectivelysuppressing a processing liquid supplied to a substrate from beingscattered and adhered again onto the substrate, while reducing a load onan exhaust apparatus that exhaust a cup.

The present disclosure provides a substrate processing apparatusincluding: a substrate holding unit configured to hold a substratehorizontally; a rotation driving mechanism configured to rotate thesubstrate holding unit around a vertical axis; a processing liquidnozzle configured to supply a processing liquid to a peripheral portionof the substrate held by the substrate holding unit; a cup configured toreceive the processing liquid scattered outwardly from the substrate,the cup having an upper opening and enclosing the periphery of thesubstrate held by the substrate holding unit; an exhaust port configuredto exhaust the interior space of the cup; and a ring-shaped cover memberhaving a lower surface and an internal peripheral surface, in which thecover member covers the peripheral portion of the upper surface of thesubstrate held by the substrate holding unit, a central portion of thesubstrate located at an inner position than the peripheral portion in aradial direction is exposed without being covered by the cover member, agap is formed between the lower surface of the cover member and theperipheral portion of the upper surface of the substrate held by thesubstrate holding unit, and when the interior space of the cup isexhausted, a gas present above the interior space of the cup isintroduced from a space enclosed by the internal peripheral surface ofthe cover member through the gap into the interior space of the cup.

In the above-described substrate processing apparatus, an internaldiameter of the lower portion of the internal peripheral surface of thecover member becomes larger as it goes downwardly. Further, a lower endof the internal peripheral portion and an internal peripheral portion ofthe lower surface in the cover member are connected to each other so asto be a curved surface.

In the above-described substrate processing apparatus, an internalperiphery of the lower surface of the cover member is located at aninner position than an external peripheral end of the substrate held bythe substrate holding unit, and an external periphery of the lowersurface of the cover member is located at an outer position than anexternal periphery of the substrate held by the substrate holding unit.Further, the internal periphery of the lower surface of the cover memberis located at an inner position than an internal periphery of theperipheral portion of the substrate held by the substrate holding unit.

In the above-described substrate processing apparatus, an opening areaof the gap is larger than that of the exhaust port.

In the above-described substrate processing apparatus, the cup has anupper opening into which the lower portion of the cover member isinserted, and a wall that defines the upper opening of the cup isprovided with a folded portion that extends downwardly.

The substrate processing apparatus further includes a moving mechanismconfigured to move the cover member between a processing position thatcomes close to the upper surface of the substrate held by the substrateholding unit and a retreat position apart from the substrate.

Further, the present disclosure provides a substrate processing methodincluding: holding a substrate horizontally in a state where theperiphery of the substrate is enclosed by a cup, and an upper side ofthe substrate is covered by a ring-shaped cover member; and performing aliquid processing on the substrate by supplying a processing liquid to aperipheral portion of the substrate in a state where the interior spaceof the cup is exhausted and the substrate is rotated around a verticalaxis, in which, when the liquid processing is performed on thesubstrate, the cover member covers the peripheral portion of an uppersurface of the substrate held by the substrate holding unit, a centralportion of the substrate located at an inner position than theperipheral portion in a radial direction is exposed without beingcovered by the cover member, a gap is formed between a lower surface ofthe cover member and the peripheral portion of the upper surface of thesubstrate held by the substrate holding unit, and when the interiorspace of the cup is exhausted, a gas present above the interior space ofthe cup is introduced from a space enclosed by the internal peripheralsurface of the cover member through the gap into the interior space ofthe cup.

In the substrate processing method, the gas flows horizontally andoutwardly through the gap between the lower surface of the cover memberand the peripheral portion of the upper surface of the substrate.

According to the present disclosure, since a ring-shaped cover member isused cover a peripheral portion of a substrate, flow resistance may bereduced in a fluid path (gap) formed between a lower surface of thecover member and an upper surface of the substrate, thereby reducing aload of the exhaust apparatus that exhausts a cup. Further, by a gasflowed outwardly from the substrate through the gap formed between thelower surface of the ring-shaped cover member and the upper surface ofthe substrate, a processing liquid supplied to a substrate may beprevented effectively from being scattered and adhered again onto thesubstrate.

An exemplary embodiment of a substrate processing apparatus of thepresent disclosure will be described with respect to a liquid apparatusthat supplies a hydrofluoric acid (HF) solution, which is a chemicalliquid, to a surface of a wafer W, which is a disc-shaped substratewhere semiconductor devices are formed, to remove an unnecessary filmformed on the peripheral portion of the wafer W.

As illustrated in FIG. 1 and FIG. 2, a liquid processing apparatus 1includes a wafer holding unit 3 configured to hold a wafer W rotatablyaround a vertical axis in a horizontal posture; a cup 2 configured toenclose the periphery of the wafer W held on the wafer holding unit 3and receives a processing liquid scattered from the wafer W; a covermember 5 configured to cover a peripheral portion of an upper surface ofthe wafer W held in the wafer holding unit 3; a elevation mechanism(moving mechanism) 6 configured to move up and down the cover member 5;and a processing fluid supplying unit 7 configured to supply aprocessing fluid to the wafer W held in the wafer holding unit 3.

The constitutional elements of the liquid processing apparatus asdescribed above such as, for example, the cup 2, the wafer holding unit3, and the cover member 5, are accommodated in one housing 11. A cleanair introducing unit 14 configured to introduce clean air from theoutside is provided in the vicinity of the ceiling of the housing 11.Further, an exhaust port 15 configured to exhaust the atmosphere in thehousing 11 is provided in the vicinity of the bottom surface of thehousing 11. As a result, downflow of the clean air is formed in thehousing 11, flowing from the upper portion of the housing 11 towards thelower portion. A carrying-in/out port 13 is provided at a side wallwhich is opened/closed by a shutter 12. A transportation arm (notillustrated) provided outside the housing 11 may pass through thecarrying-in/out port 13 in a state where the wafer W is held thereon.

The wafer holding unit 3 is constituted with a disc-shaped vacuum chuck,and the upper surface of the wafer holding unit 3 is formed as a waferadsorption surface 31. A suction port 32 is opened at the centralportion of the wafer adsorption surface 31. A hollow cylindricalrotation shaft 44 extends vertically from the central portion of thelower surface of the wafer holding unit 3. A suction conduit (notillustrated) passes through the interior space of the rotation shaft 44and is connected to the suction port 32. The suction conduit isconnected to a vacuum pump 42 in the outside of the housing 11. When thevacuum pump 42 is driven, the wafer W may be sucked by the wafer holdingunit 3.

The rotation shaft 44 is supported in a bearing casing 45 in which abearing 451 is embedded, and the bearing casing 45 is supported on thebottom surface of the housing 11. The rotation shaft 44 may be rotatedat a predetermined speed by a rotation driving mechanism 46 including adriven pulley 461 on the rotation shaft 44, a driving pulley 462 on arotation shaft of a driving motor 463, and a driving belt 464 extendingbetween the driven pulley 461 and the driving pulley 462.

As illustrated in FIG. 3, the cup 2 is a bottomed annular memberconfigured to enclose the external periphery of the wafer holding unit3. The cup 2 serves to receive and recover the chemical liquid scatteredoutwardly from the wafer W after the chemical liquid is supplied to thewafer W, and eject the chemical liquid to the outside.

A relatively small gap (e.g., having a height of about 2 mm to 3 mm) isformed between the lower surface of the wafer W held by the waferholding unit 3 and the upper surface 211 of an internal peripheral sideportion 21 of the cup 2 facing the lower surface of the wafer W. Two gasejection ports 212, 213 are opened on the upper surface 211 which isopposite to the wafer W. The two gas ejection ports 212, 213 extendcontinuously along the concentric large-diameter circumference andsmall-diameter circumference, respectively, and eject hot N₂ gas (heatednitrogen gas) towards the lower surface of the wafer W in a radiallyoutward and obliquely upward direction.

The N₂ gas is supplied from one or a plurality of gas introduction lines214 (only one illustrated in the figure) formed in the inside of theinternal peripheral side portion 21 of the cup 2 to an annular gasdiffusion space 215. The N₂ gas flows through the gas diffusion space215 while spreading in the circumferential direction, and is ejectedfrom the gas ejection ports 212, 213. A heater 216 is provided in thevicinity of the gas diffusion space 215. Accordingly, the N₂ gas isheated when the flowing through the gas diffusion space 215, and then,ejected from the gas ejection ports 212, 213. The N₂ gas ejected fromthe gas ejection port 213, which is disposed radially outside, heats upthe peripheral portion of the wafer W, which is a part to be processed,to promote reaction with the chemical liquid. Also, the N₂ gassuppresses the mist of the processing liquid, which has been ejectedtowards the front surface (upper surface) of the wafer W and thenscattered, from coming back to the back surface (lower surface) of thewafer. The N₂ gas ejected from the gas ejection port 212, which isdisposed radially inside, suppresses deformation of the wafer W. Thedeformation may be caused because only the peripheral portion of thewafer W may be heated unless the gas ejection port 212 is provided and anegative pressure is generated near the lower surface of the wafer W atthe central side of the wafer W.

In an external peripheral portion 21 of the cup 2, two top-openedannular recesses 241, 242 are formed along the peripheral direction ofthe cup 2. The recesses 241, 242 are partitioned from each other by anannular separation wall 243. A drain path 244 is connected to the bottomof the outer recess 241. Further, an exhaust port 247 is provided in thebottom of the inner recess 242, and an exhaust path 245 is connected tothe exhaust port 247. An exhaust apparatus 246 such as, for example, anejector or a vacuum pump, is connected to the exhaust path 245. Duringthe operation of the liquid processing apparatus 1, the interior spaceof the cup 2 is normally exhausted to maintain the pressure in theinside of the inner recess 242 lower than the pressure in the inside ofthe housing 11 in the outside of the cup 2.

A ring-shaped guide plate 25 extends from the external periphery of theinternal peripheral portion 21 of the cup 2 (a downward position of theperipheral portion of the wafer W) towards the radial outside. The guideplate 25 is inclined to become lower as it goes in the radial direction.The guide plate 25 covers the entire inner recess 242 and the upside ofthe internal peripheral portion of the outer recess 241. The front end251 of the guide plate 25 (the radial external peripheral portion) isbent downwardly and enters into the outer recess 241.

Further, an external peripheral wall 26 which is continuous with anouter wall surface of the outer recess 241 is provided in the externalperiphery of the external peripheral portion 24 of the cup 2. The outerperipheral wall 26 receives fluid (e.g., liquid droplets, gas or amixture thereof) scattered outwardly from the wafer W by the internalperipheral surface thereof, and guides the fluid towards the outerrecess 241. The external peripheral wall 26 includes a fluid receivingsurface 261 in the inside thereof which is inclined at an angle of 25°to 30° with respect to the horizontal surface to be lowered towards theradial outside, and a folded portion 262 that extends downwardly fromthe upper end of the fluid receiving surface 261. In the example asillustrated, the fluid receiving surface 261 formed as an inclinedsurface is connected via a horizontal surface 263 to the folded portion262. However, a curved surface may be provided instead of the horizontalsurface 263, or the folded portion 262 may be connected directly to theupper end of the fluid receiving surface 261 without the horizontalsurface 263. An exhaust fluid path 27 that allows gas (e.g., air or N₂gas) and liquid droplets scattered from the wafer W to flow is formedbetween an upper surface 252 of the guide plate 25 and the fluidreceiving surface 261. Meanwhile, the upper opening of the cup 2 isdefined by the internal peripheral surface of the folded portion 262,but the opening diameter of the upper opening is slightly larger thanthe diameter of the wafer W.

A mixed fluid of the gas and the liquid droplets introduced through theexhaust fluid path 27 into the outer recess 241 flows between the guideplate 25 and the separation wall 243 and is introduced into the innerrecess 242. When the mixed fluid passes between the guide plate 25 andthe separation wall 243, the flow direction of the mixed fluid issharply turned. Accordingly, the liquid (droplets) included in the mixedfluid is separated from the fluid by collision with the front end 251 ofthe guide plate 25 or the separation wall 243, introduced into the outerrecess 241 along the lower surface of the guide plate 25 or the surfaceof the separation wall 243, and discharged from the drain path 244. Thefluid in which liquid droplets have been removed is introduced into theinner recess 242, and then, discharged from the exhaust path 245.

The cover member 5 is a ring-shaped member disposed to face theperipheral portion of the upper surface of the wafer W when theprocessing is performed. As described below, the cover member 5rectifies gas that flows near the peripheral portion of the uppersurface of the wafer W and is drawn into the cup 2, and increases a flowrate of the gas, thereby suppressing the processing liquid scatteredfrom the wafer W from being adhered again onto the upper surface of thewafer W.

As illustrated in FIG. 3, the cover member 5 includes an internalperipheral surface 51, and a horizontal lower surface 52 facing thewafer W. The internal peripheral surface 51 has an upper side portion511 that extends vertically and a lower side portion 512 that isinclined to be directed towards the radial outside as it comes close tothe wafer W. A vertical gap G is formed between the lower side portion512 and the upper surface of the wafer W. An external periphery 521 ofthe cover member 5 is located at an outer position than an externalperipheral end We of the wafer W in a radial direction. Further, aninternal periphery 53 of the lower surface 52 of the cover member 5 islocated at an inner position than an internal periphery Wi of aperipheral portion Wp of the wafer W in the radial direction.Accordingly, an air current passing through the gap G flows horizontallyforwards the outside of the wafer W, at least in the peripheral portionWp of the wafer W. Here, the “peripheral portion Wp of the wafer W”refers to an annular region in which a device is not formed. The“internal periphery Wi of the peripheral portion Wp of the wafer Wrefers to a circumscribed circle of a device forming region, that is, acircle which takes the center of the wafer W as a center and has aminimum radius determined so that the device forming region is notincluded at all in the outside of this circle) to the externalperipheral end We of the wafer W. A radial width of the peripheralportion Wp of the wafer W, that is, a radial distance from the externalperipheral end We to the internal periphery Wi of the peripheral portionWp of the wafer W is, for example, about 3 mm.

FIG. 2 is a plan view illustrating a state where the wafer W is held onthe wafer holding unit 3 and the cover member 5 is located at aprocessing position. In FIG. 2, the external peripheral end (edge) We ofthe wafer which is covered with the cover member 5 is illustrated by thedashed line. In addition, the internal periphery of the cover member 5is represented by the reference numeral 5 e. As such, since the centralportion of the cover member 5 is opened, the flow resistance of thefluid path formed between the lower end of the cover member and thewafer W becomes smaller as compared with the disc-shaped cover memberthat covers the substantially entire surface of the wafer in the relatedart. Accordingly, even if the exhaust capability to exhaust the interiorspace of the cup 2 is low, sufficient exhaust may be performed. Further,since most of the upper surface of the wafer W excluding the peripheralportion is not covered by the cover member 5, the surface of the wafer Wmay be monitored during the processing, for example, by providing acamera in the housing 11. Further, the surface of the wafer W may alsobe checked during the processing by providing a transparent window inthe housing 11.

As illustrated in FIGS. 1 and 2, the elevation mechanism 6 configured tomove up and down the cover member 5 includes a plurality (four in thisexample) of sliders 61 fixed to a support 58 that supports the covermember 5, and guide pillars 62 that penetrate the respective sliders 61and extend vertically. A linear actuator, for example, a rod 631 of acylinder motor 63 is connected to each of the respective sliders 61.When the cylinder motor 63 is driven, the slider 61 is moved up and downalong the guide pillar 62, and thus, is capable of moving up and downthe cover member 5. The cup 2 is supported by a lifter 65 thatconstitutes a part of a cup elevation mechanism (details are notillustrated). As the lifter 65 is moved down from the state illustratedin FIG. 1, the cup 2 descends, and thus, the wafer W may be transferredbetween a transportation arm of a wafer transportation mechanism (notillustrated) and the wafer holding unit 3.

Next, referring to FIGS. 1, 2 and 4, the processing fluid supplying unit7 will be described. Particularly, as clearly illustrated in FIG. 2, theprocessing fluid supplying unit 7 includes a chemical liquid nozzle 71configured to eject a chemical liquid (HF in this example), a rinsenozzle 72 configured to eject a rinse liquid (deionized water (DIW) inthis example), and a gas nozzle 73 configured to eject a gas for drying(N₂ gas in this example). The chemical liquid nozzle 71, a rinse nozzle72 and a gas nozzle 73 are attached to a common nozzle holder 74. Thenozzle holder 74 is attached to a linear actuator, for example, a rod751 of a cylinder motor 75, which is in turn attached to the support 58configured to support the cover member 5. When the cylinder motor 75 isdriven, a supply position of the processing fluid onto the wafer W maybe moved from the nozzles 71 to 73 in a radial direction of the wafer W.

As illustrated in FIGS. 2 and 4A, the nozzles 71 to 73 are accommodatedin a recess 56 which is formed in the internal peripheral surface of thecover member 5. The respective nozzles 71 to 73 direct obliquelydownwardly, as illustrated by an arrow A in FIG. 4B, and also, dischargethe processing fluid such that the discharge direction represented bythe arrow A has a component of a rotation direction Rw of the wafer. Bydoing this, it is possible to suppress generation of mist (liquiddroplet generated due to collision of the processing liquid with thewafer W) which may be generated in a case where the processing fluid isliquid. The processing fluid is supplied from processing fluid supplymechanisms 711, 721, 731 as schematically illustrated in FIG. 2 to therespective nozzles 71 to 73. Each of the processing liquid supplymechanisms 711, 721, 731 may be constituted by a processing fluid supplysource such as a tank, a pipeline that supplies the processing fluidfrom the processing fluid supply source to the nozzles, and a flowcontrol device such as an opening/closing valve or a flow-rate adjustingvalve installed in the pipeline.

Further, as illustrated in FIG. 3, in the internal peripheral sideportion 21 of the cup 2, a plurality (only one illustrated in thefigure) of processing liquid ejection ports 22 are formed at differentpositions with respect to the circumferential direction outside of thegas ejection port 213. The respective processing liquid ejection ports22 eject the processing fluid outwardly from the wafer W and obliquelyupwardly towards the peripheral portion of the lower surface of thewafer W. From at least one of the processing liquid ejection ports 22,the same chemical liquid as the chemical liquid ejected from thechemical liquid nozzle 71 may be ejected. Further, from at least anotherone of the processing liquid ejection ports 22, the same rinse liquid asthe rinse liquid ejected from the rinse nozzle 72 may be ejected. Asillustrated in FIG. 3, a process fluid supply mechanism 221 having thesame configuration as the above-mentioned nozzles 71 to 73 is connectedto each of the processing liquid ejection ports 22.

As schematically illustrated in FIG. 1, the liquid processing apparatus1 includes a controller (control unit) 8 configured to integrallycontrol the entire operations thereof. The controller 8 controls theoperations of all functional parts (for example, the rotation drivingmechanism 46, the elevation mechanism 6, the vacuum pump 42, and variousprocessing fluid supply mechanisms). The controller 8 may be implementedusing, for example, a general purpose computer as a hardware and aprogram (an apparatus control program and a processing recipe) tooperate the computer as a software. The software may be stored in astorage medium such as, for example, a hard disc drive which is fixedlyprovided in the computer, or in a storage medium such as, for example, aCD-ROM, a DVD and a flash memory which are removably set in thecomputer. The storage medium is indicated by a reference numeral 81 inFIG. 1. A processor 82 accesses and executes a predetermined processingrecipe from the storage medium 81 based on, for example, instructionsfrom a user interface (not illustrated) as needed. As a result, eachfunctional component of the liquid processing apparatus 1 is operated toperform a predetermined processing under the control of controller 8.

Next, description will be made on the operation of the liquid processingapparatus 1 performed under the control of the controller 8.

[Carry-in of Wafer]

First, the cover member 5 is disposed at a retreat position (upperposition in FIG. 1), and the cup 2 is moved down by the lifter 65 of thecup elevation mechanism. Subsequently, a shutter 12 of the housing 11 isopened to allow a transportation arm (not illustrated) of an externalwafer transportation mechanism (not illustrated) to enter the housing11. Then, the wafer W held by the transportation arm is disposed justabove the wafer holder 3. Subsequently, the transportation arm is moveddown to a position lower than the upper surface of the wafer holder 3 todispose the wafer W on the upper surface of the wafer holder 3. Next,the wafer W is adsorbed by the wafer holder 3. Thereafter, the emptytransportation arm exits from the inside of the housing 11. Then, thecup 2 is moved up to return to the position as illustrated in FIG. 1,and the cover member 5 is moved down to the processing position asillustrated in FIG. 1. By the above-mentioned procedure, the carry-in ofthe wafer is completed, and is in a state as illustrated in FIG. 1.

[Chemical Liquid Processing]

Next, a chemical liquid processing is performed on the wafer W. Thewafer W is rotated at a predetermined speed (e.g., 2,000 rpm). Inaddition, hot N₂ gas is ejected from the gas ejection ports 212, 213 ofthe cup 2 to heat the peripheral portion of the wafer W, which is aregion to be processed, to a temperature suitable for the chemicalliquid processing (e.g., 60° C.). Further, when performing a chemicalprocessing which is not necessary to heat the wafer W, N₂ gas at normaltemperature may be ejected without operating the heater 216. When thewafer W is heated sufficiently, the chemical liquid (HF) is suppliedfrom the chemical liquid nozzle 71 to the peripheral portion of theupper surface (device forming surface) of the wafer W while rotating thewafer W, thereby removing any unnecessary film in the peripheral portionof the upper surface of the wafer. At the same time, the chemical liquidis supplied from the chemical liquid processing liquid ejection port 22to the peripheral portion of the lower surface of the wafer W, therebyremoving any unnecessary film in the peripheral portion of the lowersurface of the wafer. The chemical liquid supplied to the upper andlower surfaces of the wafer W flows while spreading outwardly bycentrifugal force, is flowed out of the wafer W together with theremoved matters, and is recovered by the cup 2. Further, while thechemical liquid processing is performed, the chemical liquid nozzle 71,which is discharging the chemical liquid by driving the cylinder motor75, may be reciprocated in the radial direction of the wafer W, therebyenhancing the uniformity of the processing.

[Rinse Processing]

After the chemical liquid processing is performed for a predeterminedperiod of time, a rinse processing is subsequently performed bycontinuing the rotation of the wafer W and the ejection of N₂ gas fromthe gas ejection ports 212, 213, stopping the ejection of the chemicalliquid from the chemical liquid nozzle 71 and the chemical liquidprocessing liquid ejection port 22, and supplying the rinse liquid (DIW)from the rinse nozzle 72 and the rinse liquid processing liquid ejectionport 22 to the peripheral portion of the wafer W. By this rinseprocessing, the chemical liquid and any reaction products remained onthe upper and lower surfaces of the wafer W are washed out.

[Dry Processing]

After the rinse processing is performed for a predetermined period oftime, a dry processing is subsequently performed by continuing therotation of the wafer W and the ejection of N₂ gas from the gas ejectionports 212, 213, stopping the ejection of the rinse liquid from the rinsenozzle 72 and the rinse liquid processing liquid ejection port 22, andsupplying the gas for drying (N₂ gas) from the gas nozzle 73 and therinse liquid processing liquid ejection port 22 to the peripheralportion of the wafer W. By the above procedure, a series of processingsfor the wafer W is completed.

[Carry-Out of Wafer]

Thereafter, the cover member 5 is moved up to be disposed at the retreatposition, and the cup 2 is moved down. Subsequently, the shutter 12 ofthe housing 11 is opened to allow the transportation arm (notillustrated) of the external wafer transportation mechanism (notillustrated) to enter the housing 11. Then, the empty transportation armis disposed below the wafer W held by the wafer holder 3, and then,moved up to receive the wafer W from the wafer holder 3 in a state wherethe adsorption of the wafer W is stopped. Thereafter, the transportationarm holding the wafer W exits from the inside of the housing 11. By theabove-mentioned procedure, a series of processings for one wafer iscompleted in the liquid processing apparatus.

Next, referring to FIGS. 3 to 5, descriptions will be made in detail onthe flow of the fluid in the vicinity of the peripheral portion of thewafer and the configuration of the cup 2 and the cover member 5 relatedto the flow of the fluid.

The interior space of the cup 2 is exhausted through the exhaust path245 and becomes a negative pressure, the gas above the upper surface ofthe wafer W (a clean air forming a downflow in the housing 11) is drawnthrough the gap G into the exhaust fluid path 27. Further, the N2 gasejected from the gas ejection ports 212, 213 is flowed out of the spacebetween the upper surface 211 of the internal peripheral portion 21 andthe lower surface of the wafer W by an influence of the rotation of thewafer W, and flowed into the exhaust fluid path 27. Such flow of the gasis illustrated in FIG. 5B.

Since the lower side portion 512 of the internal peripheral surface 51of the cover member 5 is inclined to be directed towards the radialoutside as it comes close to the wafer W (that is, since the internaldiameter of the lower portion of the internal peripheral surface 51 ofthe cover member 5 is formed so as to be larger as it goes downwardly),the gas is flowed into the gap G smoothly as compared with a case wherethe internal peripheral surface 51 is a single vertical surface.Accordingly, disorder of the air current hardly occurs even in the gapG. Further, a joint between the internal peripheral surface 51 of thecover member 5 and the lower surface 52 may not be made an edge (as theinternal periphery 53 indicated by the reference numeral 53 in FIG. 3),but the internal peripheral surface 51 and the lower surface 52 may bemade as a curved surface (see an arrow indicated by the referencenumeral R in FIG. 5B). The R shape is also suitable for smoothlyintroducing the gas into the gap G.

Meanwhile, the chemical liquid supplied from the chemical liquid nozzle71 to the peripheral portion of the upper surface of the wafer W and thechemical liquid supplied from the chemical liquid processing liquidejection port 22 to the peripheral portion of the lower surface of thewafer W, are diffused towards the peripheral portion of the wafer bycentrifugal force and scattered outwardly from the wafer W. Most of thechemical liquid on the upper surface of the wafer W is scattered towardsa region A_(R) interposed between two arrows A₁, A₂ at the upper side inFIG. 5A. The chemical liquid is scattered the most and also the moststrongly in the horizontal direction (direction of the arrow A₁), andthe amount and force of the chemical liquid scattered are reduced as thescattering direction approaches a direction represented by the arrow A₂.Most of the chemical liquid on the lower surface of the wafer W isscattered towards a region B_(R) interposed between two arrows B₁, B₂ atthe lower side in FIG. 5A. The chemical liquid is scattered the most andalso the most strongly in the horizontal direction (direction of thearrow B₁), and the amount and power of the chemical liquid scattered arereduced as the scattering direction approaches a direction representedby the arrow B₂. As described above, the chemical liquid is scatterednot only by centrifugal force, but also by an influence of the flow ofthe gas (clean air) that is flowed out horizontally at a graduallyincreasing speed when passing through the gap G between the cover member5 and the wafer W. Meanwhile, the liquid (chemical liquid or rinseliquid) supplied to the upper surface of the wafer W does not come intocontact with the lower surface 52 of the cover member 5.

The chemical liquid scattered from the wafer W flows down along thefluid receiving surface 261 and the upper surface 252 of the guide plate25 towards the recess 241 at the outside of the cup 2, or becomesmicrodroplet (mist) and flows along the air current within the exhaustfluid path 27 as illustrated in FIG. 5B. The arrow illustrated as abroken line in FIG. 5B represents the air current, and the flow of themist inside the exhaust fluid path 27 almost accords with the aircurrent inside the exhaust fluid path 27. Meanwhile, although the liquiddroplet inside the exhaust fluid path 27 proceeds through the gap Gbetween the lower surface 52 of the cover member 5 and the upper surfaceof the wafer W to the central portion of the wafer W, such movement ofthe liquid droplet is disturbed by the above-mentioned air current thatflows outwardly from the wafer W. As a result, it is possible tosuppress the contamination of the wafer caused by the chemical liquidscattered from the wafer W and adhered again thereto.

In addition to the above-mentioned configuration, in order to preventcontamination of the wafer W due to the re-adhesion of the chemicalliquid scattered from the wafer W, the cup 2 and the cover member 5according to the present exemplary embodiment further include anadvantageous configuration as follows.

In order to suppress bounce of the chemical liquid which is stronglyincident on the fluid receiving surface 261 of the cup 2, the angleformed by the fluid receiving surface 261 of the cup 2 in relation tothe horizontal surface (this is the same as the incident angle θ atwhich the flow of the chemical liquid indicated by the arrows A₁, B₂ isincident on the fluid receiving surface 261) is set to a relativelysmall value, for example, 30°. Accordingly, the scattering of thechemical liquid caused by the collision of the chemical liquid with thefluid receiving surface 261 may be reduced.

For the gap G between the lower surface 52 of the cover member 5 and theupper surface of the wafer W, an opening area (which means an area of acylindrical surface having the same as a distance from the central axisof the cover member 5 to the internal periphery 53 of the lower surface52, and a height G₁ (height of the gap G) of the gap G is set to beequal to or greater than an area of the exhaust port 247. Accordingly,the gas present above the upper surface of the wafer W can be drawnsmoothly. If the gap G is too narrow, the flow resistance of the gap Gbecomes higher, and thus, sufficient exhaust cannot be achieved with asmall exhaust force. The height G₁ of the gap G may be, for example, 4mm to 5 mm.

Further, a radial width G₂ (a length in which the lower surface of thecover member 5 and the wafer W overlap in the radial direction) is about4 mm to 6 mm, for example, 5 mm. If the width G₂ is too large, the flowresistance of the gap G becomes higher, and thus, sufficient exhaustcannot be achieved with a small exhaust force. Meanwhile, if the widthG₂ is too small, it is not preferred in that the flow of the gas insidethe gap G is disturbed (it is preferred that the gas inside the gap Gflows horizontally towards the radial outside). Meanwhile, the optimalvalue of the width G₂ varies in relationship with the height G₁.

A distance D₁ between the fluid receiving surface 261 and the uppersurface 252 of the guide plate 25 becomes gradually smaller as it goesdownstream (as it approaches the recess 241 at the outside of the cup2). By doing this, generation of a backflow of the air current may beprevented.

Since the cup 2 is provided with the folded portion 262, even ifbackflow of air current occurs as indicated by an arrow F_(R1) in FIG.5B, the backflow is turned to the downstream side as indicated by anarrow F_(R2), by the folded portion 262. Accordingly, the mist of thechemical liquid entrained in the air current indicated by the arrowF_(R1) is suppressed from being directed to the wafer W.

Further, the height of the front end (lower end) of the folded portion262 of the cup 2 is preferably the same as that of the lower surface 52of the cover member 5. In this way, disorder of the gas hardly occurswhen flowing through the gap G. A slight difference in height betweenboth sides may be allowed, but, if the front end of the folded portion262 is at a too low position, there may be a concern that the mist ofthe chemical liquid scattered from the surface of the wafer W (see thearrow A₂ in FIG. 5A) collides with the folded portion 262 and bouncestowards the wafer W. On the other hand, if the front end of the foldedportion 262 is at a too high position, it is difficult to sufficientlyprevent the mist of the chemical liquid riding the air current asindicated by the arrow F_(R1) in FIG. 6 from directing towards the waferW. Meanwhile, the distance between the peripheral portion 521 of thelower surface 52 of the cover member 5 and the folded portion 262(distance measured in the radial direction of the wafer) is preferablyas small as possible, so long as it is guaranteed that the periphery 521does not collide with the cup 2 when the cover member 5 is moved up. Asa result, the gas that has passed through the gap G is prevented fromforming turbulence in the space between the periphery 521 and the foldedportion 262.

When the cover member 5 is located at the processing position, it ispreferred that the space between the cover member 5 and the uppersurface of the external peripheral wall 25 is sealed by a seal member59, as illustrated in FIG. 3. Accordingly, since the gas inside thehousing 11 is introduced solely through the gap G into the exhaust fluidpath 27, disorder of the air current hardly occurs in the vicinity ofthe external periphery of the wafer W, and a load on the exhaustapparatus 246 may be reduced as well.

Meanwhile, the flows of air current and mist in the chemical liquidprocessing have been described above. However, it is evident that theflows of air current and mist are also generated similarly in the rinseprocessing.

The liquid processing performed by the liquid processing apparatus 1 isnot limited to the foregoing. For example, the chemical liquid is notlimited to HF, but may be SC-1 or SC-2. Further, the chemical liquidprocessing may be performed several times. In addition, the substrate tobe processed is not limited to a semiconductor wafer, but may be variouscircular substrates of which the peripheral portion is required to becleaned, for example, a glass substrate and a ceramic substrate.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims.

What is claimed is:
 1. A substrate processing apparatus comprising: ahousing; a clean gas introducing unit provided in a ceiling of thehousing and a vicinity thereof, and configured to introduce clean gas toan interior of the housing; a substrate holding unit configured to holda substrate horizontally; a rotation driving mechanism configured torotate the substrate holding unit around a vertical axis; a processingliquid nozzle configured to supply a processing liquid, the nozzle beingaimed at a peripheral portion of an upper surface of the substrate heldby the substrate holding unit; a cup provided below the clean gasintroducing unit and configured to receive the processing liquidscattered outwardly from the substrate, the cup having an upper openingand enclosing the peripheral portion of the substrate held by thesubstrate holding unit; an exhaust port integrally provided in the cupand configured to exhaust an interior space of the cup formed below theperipheral portion of the substrate held by the substrate holding unitsuch that a pressure of the interior space of the cup becomes a negativepressure when the interior space of the cup is exhausted through theexhaust port; and a ring-shaped cover member formed along the upperopening of the cup, and having a lower surface and an internalperipheral surface, wherein the ring-shaped cover member covers theperipheral portion of the upper surface of the substrate held by thesubstrate holding unit, and a central portion of the ring-shaped covermember is opened such that a central portion of the substrate is exposedto the interior of the housing, and a vertical gap is formed between thelower surface of the ring-shaped cover member and the peripheral portionof the upper surface of the substrate held by the substrate holdingunit, and when the interior space of the cup is exhausted through theexhaust port, the clean gas introduced from the clean gas introducingunit is introduced from a space enclosed by the internal peripheralsurface of the ring-shaped cover member into the interior space of thecup through the vertical gap formed between the lower surface of thering-shaped cover member and the peripheral portion of the upper surfaceof the substrate held by the substrate holding unit, thereby generatingan air current above the peripheral portion of the substrate flowingthrough the vertical gap in a horizontal direction to reach the interiorspace of the cup and suppressing the processing liquid scatteredoutwardly from the substrate from being reattached to the substrate. 2.The substrate processing apparatus of claim 1, wherein an internaldiameter of a lower portion of the internal peripheral surface of thering-shaped cover member becomes larger as it goes downwardly, and alower end of the internal peripheral portion and an internal peripheralportion of the lower surface in the ring-shaped cover member areconnected to each other so as to be a curved surface.
 3. The substrateprocessing apparatus of claim 2, wherein an opening area of the gap islarger than that of the exhaust port.
 4. The substrate processingapparatus of claim 1, wherein the cup has an upper opening into whichthe lower portion of the ring-shaped cover member is inserted, and awall that defines the upper opening of the cup is provided with a foldedportion that extends downwardly.
 5. The substrate processing apparatusof claim 1, further comprising a moving mechanism configured to move thering-shaped cover member between a processing position that comes closeto the upper surface of the substrate held by the substrate holding unitand a retreat position apart from the substrate.
 6. The substrateprocessing apparatus of claim 2, wherein the cup has an upper openinginto which the lower portion of the ring-shaped cover member isinserted, and a wall that defines the upper opening of the cup isprovided with a folded portion that extends downwardly.
 7. The substrateprocessing apparatus of claim 1, wherein a recess is formed in theinternal peripheral surface of the ring-shaped cover member, and theprocessing liquid nozzle is accommodated in the recess.
 8. The substrateprocessing apparatus of claim 1, wherein an inner recess and an outerrecess each having an upper opening are provided in an externalperipheral portion of the cup along a circumference of the cup, anannular separation wall is provided between the two recessespartitioning the two recesses from each other, and the exhaust port isformed on a bottom of the inner recess and a drain path is formed on abottom of the outer recess.
 9. A substrate processing apparatuscomprising: a substrate holding unit configured to hold a substratehorizontally; a rotation driving mechanism configured to rotate thesubstrate holding unit around a vertical axis; a processing liquidnozzle configured to supply a processing liquid, the nozzle being aimedat a peripheral portion of an upper surface of the substrate held by thesubstrate holding unit; a cup configured to receive the processingliquid scattered outwardly from the substrate, the cup having an upperopening and enclosing the peripheral portion of the substrate held bythe substrate holding unit; an exhaust port integrally provided in thecup and configured to exhaust an interior space of the cup formed belowthe peripheral portion of the substrate held by the substrate holdingunit such that a pressure of the interior space of the cup becomes anegative pressure when the interior space of the cup is exhaustedthrough the exhaust port; and a ring-shaped cover member formed alongthe upper opening of the cup, and having a lower surface and an internalperipheral surface, wherein the ring-shaped cover member covers theperipheral portion of the upper surface of the substrate held by thesubstrate holding unit, and a central portion of the ring-shaped covermember is opened such that a central portion of the substrate located atan inner position than the peripheral portion in a radial direction isexposed without being covered by the ring-shaped cover member, avertical gap is formed between the lower surface of the ring-shapedcover member and the peripheral portion of the upper surface of thesubstrate held by the substrate holding unit, and when the interiorspace of the cup is exhausted through the exhaust port, a clean gassupplied from above an interior space of the cup formed below theperipheral portion of the substrate held by the substrate holding unitis introduced from a space enclosed by the internal peripheral surfaceof the ring-shaped cover member into the interior space of the cupthrough the vertical gap formed between the lower surface of thering-shaped cover member and the peripheral portion of the upper surfaceof the substrate held by the substrate holding unit, thereby generatingan air current above the peripheral portion of the substrate flowingthrough the vertical gap in a horizontal direction to reach the interiorspace of the cup and suppressing the processing liquid scatteredoutwardly from the substrate from being reattached to the substrate. 10.The substrate processing apparatus of claim 9, wherein an internaldiameter of a lower portion of the internal peripheral surface of thering-shaped cover member becomes larger as it goes downwardly, and alower end of the internal peripheral portion and an internal peripheralportion of the lower surface in the ring-shaped cover member areconnected to each other so as to be a curved surface.
 11. The substrateprocessing apparatus of claim 9, wherein a recess is formed in theinternal peripheral surface of the ring-shaped cover member, and theprocessing liquid nozzle is accommodated in the recess.
 12. Thesubstrate processing apparatus of claim 8, wherein a ring-shaped guideplate is provided to be extending from an external periphery of aninternal peripheral portion of the cup below the peripheral portion ofthe substrate toward a radial direction, and configured to cover anentire upper opening of the inner recess.
 13. The substrate processingapparatus of claim 12, wherein a front end of the ring-shaped guideplate is bent downwardly as it approaches in a radial direction andenters into the upper opening of the outer recess.